LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Ford >> 1990 >> Probe LX, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 3.0L >> Test N - Ignition Diagnostic Monitor (IDM) >> TFI Module Distributor
April 5, 2026: LEMON Manuals is launched! Read the announcement.

TFI Module Distributor

This is the most common system. The TFI module is mounted in the distributor and a single module connector is used.

IGNITION SYSTEM APPLICATIONS

Vehicle Application
3.0L SHO PFI DIS
All Others TFI

1) Continuous Memory Code 14: Erratic Ignition  Code 14 indicates 2 successive erratic Profile Ignition Pickup (PIP) pulses occurred, resulting in a possible engine miss or stall. If vehicle is a NO START and has a Code 14, go directly to TEST AA, step 1). Possible causes for this fault are:

If any of the above are present, service as necessary, clear code and rerun QUICK TEST. If the items listed are not present, go to step 4).

2) Code 16: IDM Circuit Failure (EDIS)  If engine does not start, see EDIS ignition system in the I - SYS/COMP TESTS article. If engine starts, go to step 4).

3) Continuous Memory Code 18: Check For Other Codes  A Code 18 indicates a loss of IDM input signal to the ECA. Possible causes for this fault are:

If Continuous Memory Codes 45, 46 or 48 are present, see DIS or EDIS testing in I - SYS/COMP TESTS. If Codes 45, 46 or 48 are not present, go to next step.

4) Continuous Memory Codes 18, 28 or 48: Check IDM Circuit Continuity  Code 18 indicates a loss of IDM input signal. Possible causes are:

Code 28 indicates the IDM input signal is always low. Possible causes are:

Code 48 indicates IDM input signal always high. Possible causes are:

NOTE: On TFI vehicles the IDM circuit has a 22 k/ohm-resistor between Test Pin No. 4 and the ignition coil negative terminal (except 3.0L CALIFORNIA vehicles).

Turn key off an wait 10 seconds. Disconnect E-core ignition coil on TFI vehicles and DIS module connector (pins No. 7-12) on DIS equipped vehicles. Disconnect EDIS module (if equipped). Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leave ECA connected and set DVOM on 200-k/ohm scale.

On TFI equipped vehicles, measure resistance between Test Pin No. 4 at breakout box and negative terminal of ignition coil harness connector.

On DIS and EDIS equipped vehicles, measure resistance between Test Pin No. 4 at breakout box and DIS module harness connector pin No. 12.

If resistance is 20-24 k/ohms (on DIS and 3.0L CALIFORNIA vehicles, resistance should be less than 5 ohms), go to step 6) for EDIS vehicles or next step for all others. If resistance is not to specification, repair open circuit, clear codes, retest and reconnect "E" core coil.

5) Check IDM Circuit For Short to Ground  Turn key off and wait 10 seconds. Disconnect "E" core ignition coil on TFI vehicles and DIS module connector (pins No. 7-12) on DIS equipped vehicles. Disconnect EDIS module on EDIS equipped vehicles. Install breakout box and leave ECA disconnected. With DVOM on 200-k/ohm scale, measure resistance between Test Pin No. 4 and test pins No. 40, 46, and 60. If any reading is less than 10 k/ohms, remove breakout box, repair short to ground in IDM circuit, reconnect all components and rerun QUICK TEST. If any readings is 10 k/ohms or more, go to step 8).

6) Check IDM Circuit For Shorts To Power (Except VREF Circuit)  With key off, install breakout box. Disconnect ECA and EDIS module. Measure voltage between Test Pin No. 4 and test pins No. 40 and 60. To check for a short to VBAT, leave key off. To check for a short to KEYPOWER or VPWR, turn key on, leaving engine off. If any voltage reading is greater than 10.5 volts, repair short circuit. Remove breakout box and reconnect all components. Rerun QUICK TEST. If voltage is less than 10.5 volts, go to next step.

7) Check IDM Circuit For Short To VREF, GROUND & PIP  Turn key off. Install breakout box, leaving ECA disconnected. Disconnect EDIS module (if equipped). For shorts to ground, measure resistance between Test Pin No. 4 and test pins No. 16, 20, 40, 46 and 60.

On vehicles equipped with EDIS, a short to SIG RTN (Pin No. 46) may be indicated in conjunction with an actual PWR GND short when the 4-wire HEGO sensor is connected.

To test for shorts to VREF, measure resistance between test pins No. 36 and 26, at the breakout box.

To test for shorts to PIP, measure resistance between test pins No. 36 and 56, at the breakout box.

If each resistance is greater than 10 k/ohms, go to next step. If not, repair short circuit. Remove breakout box, reconnect all components and repeat QUICK TEST.

8) Check ECA For Short to Ground  Turn key off and wait 10 seconds. Disconnect "E" core ignition coil on TFI vehicles and DIS module connector (pins No. 7-12) on DIS equipped vehicles. Disconnect EDIS module on EDIS vehicles. Install breakout box and connect ECA. With DVOM on 200-k/ohm scale, measure resistance between Test Pin No. 4 and test pins No. 40, 46, and 60. If any reading is less than 10 k/ohms, replace ECA, reconnect all components and rerun QUICK TEST. If all readings are 10 k/ohms or more, reconnect components and go to next step.

9) Check Ignition Module  Turn key off and wait 10 seconds. Deactivate Self-Test. Using Continuous Monitor Mode (WIGGLE TEST), observe VOM or diagnostic tester for indication of fault while lightly tapping on TFI or DIS/EDIS module to simulate road shock. Wiggle all TFI or DIS harness connectors. On Closed Bowl Distributor (CBD) models, wiggle TFI and distributor hall connectors. If fault is indicated, go to next step. If not, disconnect and inspect TFI harness connectors and terminals for damage. If connector and terminals are okay, check ignition system, see SYSTEMS & COMPONENT TESTING. If ignition is okay, replace ECA.

10) Check EEC-IV Harness  While still in Continuous Monitor Mode (WIGGLE TEST), observe VOM or diagnostic tester for indication of fault while wiggling, shaking, or bending small sections of harness while working from TFI or DIS connectors toward firewall. Repeat process from firewall to ECA. On CBD systems also test distributor Hall connector. Perform this test to check for faults in the following circuits:

CONDITION-TO-CIRCUIT/TEST PIN NO. MENU

Condition: Check Circuit/Test Pin No.
PIP Open/Shorted to Ground Check circuit at Pin No. 56
SPOUT Shorted to Ground Check circuit at Pin No. 36
Ignition Ground Open Check circuit at Pin No. 16
IDM Open to Ground Check circuit at Pin No. 4
IDM Shorted to Power Check circuit at Pin No. 4

Perform Continuous Monitor Mode (WIGGLE TEST) on these circuits one at a time in order to isolate fault. If fault is indicated, isolate fault and repair harness. Repeat QUICK TEST. If no fault is indicated, go to next step.

11) Check ECA & Harness Connectors  Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion or loose wires. If connector is damaged, repair as necessary, clear codes and repeat QUICK TEST. If connector is okay, perform the following procedure based on the Continuous Memory Code displayed:

12) Continuous Memory Code 19: Check Camshaft Sensor Output  Code 19 indicates one of the 2 Cylinder Identification (CID) sensor output signals has failed. One of the outputs is a signal sent to the DIS and the second output is the signal to the ECA. Both outputs have a 50 percent duty cycle of 0.4 volt to battery voltage (VBAT). Possible causes for this fault are; open or short in CID-to-ECA circuit.

With key off, disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion or loose wires. If connector is damaged, repair as necessary. Install breakout box and connect ECA. With KOER, and DVOM set on AC scale, measure voltage between Test Pin No. 24 and GROUND. If voltage varies, replace ECA, remove breakout box, reconnect all components and rerun QUICK TEST. If voltage does not vary, go to next step.

13) Check CID Harness For Continuity  With key off and breakout box installed, disconnect ECA. Disconnect DIS module. Set DVOM on 200-ohm scale. Measure resistance between Test Pin No. 24 at the breakout box and pin No. 2 (CID signal) at the DIS module connector. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open circuit, remove breakout box, reconnect all components and rerun QUICK TEST.

14) Check CID Circuit For Shorts  Turn key off, Install breakout box, leaving ECA disconnected. Disconnect DIS module. Set DVOM on 200-k/ohm scale. Measure resistance between Test Pin No. 24 and test pins No. 16, 37 and 40 at the breakout box. If all resistances are not greater than 10 k/ohms, repair CID circuit for short to GROUND or POWER. Remove breakout box, reconnect all components and rerun QUICK TEST. If all resistances are greater than 10 k/ohms, remove breakout box, reconnect all components and diagnose TFI or DIS system. See I - SYS/COMP TESTS article.

NOTE: There is a break in the step numbering sequence at this point, skipping from step 14) to step 20). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

20) Continuous Memory Code 88: Check Continuity of DPI Circuit  Code 88 indicates an open in the Dual Plug Inhibit (DPI) circuit or an open or short to ground in coil No. 4. Possible causes for this fault are:

Turn key off and wait 10 seconds. Disconnect DIS connector (pins No. 1-6). Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion or loose wires. If connector is damaged, repair as necessary. Install breakout box and leave ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between pin No. 6 at the DIS vehicle harness connector and Test Pin No. 32 at the breakout box. If resistance is less than 5 ohms, remove breakout box, reconnect all components. Diagnose DIS ignition system. If system is okay, replace ECA. If resistance is not less than 5 ohms, repair open circuit, remove breakout box, reconnect all components and rerun QUICK TEST.

scientia non olet · About LEMON Manuals